John Boehner, the former Republican speaker of the House who once said he was “unalterably opposed” to decriminalizing marijuana laws, has joined a board of directors for a cannabis company with an eye on rolling back federal regulations. The former Ohio congressman has been appointed to the board of advisers of Acreage Holdings, invoking the need for veterans to access the drug legally to explain his change of heart, Boehner said in a statement Wednesday.…